Solar thermal energy | Simply explained | Photovoltaics vs Solar thermal systems

Summary

Solar thermal energy is a renewable resource that converts sunlight into heat rather than electricity, unlike photovoltaics. It works through heat collectors that absorb sunlight, heating a fluid (like water) that is stored for later use, such as in home heating or hot water systems. There are two types of solar thermal systems: non-concentrating and concentrating, with the latter used in industrial applications. While solar thermal systems are typically cheaper upfront, photovoltaic systems pay for themselves faster and generate electricity directly. This video explores the key differences, advantages, and applications of both solar thermal and photovoltaic technologies.

Takeaways

• 😀 Solar thermal energy is a renewable energy source that converts sunlight into thermal energy, unlike photovoltaics, which generate electricity directly.
• 😀 Solar thermal systems use heat collectors to absorb sunlight and convert it into heat, typically for applications like heating water or homes.
• 😀 Black heat collectors are commonly used in solar thermal systems because they absorb almost all light and maximize heat absorption.
• 😀 A fluid, such as water, flows through the heat collectors, absorbing the heat and transporting it to a hot water storage tank.
• 😀 Solar thermal systems can be divided into two types: non-concentrating systems, which are used for residential purposes, and concentrating systems, which are used in industrial applications.
• 😀 Non-concentrating systems, like surface collectors and vacuum tube collectors, can reach temperatures of 80-150°C.
• 😀 Concentrating systems use mirrors to focus sunlight onto a smaller area, achieving much higher temperatures (over 1000°C), often used in solar thermal power plants for industrial heat generation.
• 😀 Solar thermal power plants can generate electricity indirectly by using heat to produce steam that drives turbines connected to generators.
• 😀 Solar thermal systems are generally cheaper to purchase than photovoltaic systems, but they tend to have a longer payback period (around 20 years).
• 😀 Photovoltaic systems pay for themselves more quickly, on average in 10-15 years, but they do not store heat directly like solar thermal systems.
• 😀 In sunny, warmer climates, solar thermal systems are more commonly used for both industrial and residential purposes, as they can store heat for later use.

Q & A

What is the primary difference between solar thermal and photovoltaic systems?

The main difference is that solar thermal systems convert sunlight into thermal energy (heat), while photovoltaic systems convert sunlight directly into electrical energy.

How do solar thermal systems work?

Solar thermal systems use collectors to absorb sunlight, which is then converted into heat. A fluid, like water, circulates through the collectors, absorbs the heat, and transports it to a storage tank for later use, such as heating water or a home.

What types of solar thermal systems exist?

There are two main types of solar thermal systems: non-concentrating systems, which include flat-plate and vacuum tube collectors, and concentrating systems that use mirrors to focus sunlight, reaching much higher temperatures.

What is the purpose of using black materials in solar thermal collectors?

Black materials are used in solar thermal collectors because they absorb almost all sunlight and reflect very little, maximizing the heat yield by effectively capturing solar energy.

How do photovoltaic systems generate electricity?

Photovoltaic systems generate electricity by converting sunlight directly into electrical energy using solar cells made from semiconductors, which create an electric current when exposed to sunlight.

Can solar thermal systems generate electricity directly?

No, solar thermal systems do not generate electricity directly. They produce heat, which can then be used for heating or, in some cases, can indirectly generate electricity through processes like steam turbines.

What are the benefits of solar thermal systems compared to photovoltaic systems?

Solar thermal systems are generally cheaper to install, and they can store heat for later use, allowing for energy generation even when the sun is not shining. They are especially efficient in warmer climates with abundant sunlight.

How long does it take for solar thermal systems and photovoltaic systems to pay for themselves?

On average, a photovoltaic system pays for itself within 10 to 15 years, while a solar thermal system takes about 20 years to break even. However, these figures can vary depending on factors like location, application, and energy usage.

Why have more photovoltaic systems been installed in Germany in recent years?

Due to feed-in tariffs, rising electricity prices, and the greater use of heat pumps, photovoltaic systems have become more financially viable and are paying for themselves faster than solar thermal systems in Germany.

In what type of countries is solar thermal energy particularly beneficial?

Solar thermal energy is particularly beneficial in countries with more hours of sunlight and warmer temperatures, such as Morocco, where large solar thermal power plants are already in operation.